Product Description

serial interface information to jump-start projects on several platforms. This it the first book to have extensive on RS-485 , a widely used, industry standard interface for networks. This reference features original content based on the author's firsthand research and experience, not just rewritten specifications and marketing materials. Programmers, engineers and developers will use the designs in this book to get projects up an running quickly. Installation and maintenance staff will find tips for ensuring reliable operation and problem tracking. Students and computer enthusiast can use the book's complete, original examples and tools to design experimental projects for several computer platforms.

Product Details

• Amazon Sales Rank: #80635 in Books
• Published on: 1998-06
• Format: Illustrated
• Original language: English
• Number of items: 1
• Binding: Paperback
• 306 pages

Review
Anyone who wants to build equipment and connect it to a computer will need the information covered here. It covers everything from the basic electrical and physical parameters, cables, and basic architecture to programming for PCs and microcomputers. -- Industrial & Control Systems, October 1998

Axelson's book is about as complete a reference as you'll find on serial communications. The code could save you some time; the reference material surely will. -- Embedded Systems Programming, January 1999

Despite the book's detailed technical content, the style is clear. Although it contains enough material to satisfy most hardware and software engineers who develop products containing communication ports, the book should also prove useful to serious hobbyists. Nevertheless, despite its broad appeal, Serial Port Complete is far from watered-down pablum. -- EDN, March 4, 1999

Serial Port Complete is an accurate title. This book covers everything you'd ever want to know about serial ports and network projects. And it's not all theory. This is a very practical book, full of detailed examples - including Stamps and Visual Basic. This book is a "must-have" for serious experimenters. -- Nuts & Volts, Sept '98

The part of the book I liked most comes in the section that describes how to connect serial devices. Axelson covers not only RS-232 communications but also RS-485, a serial standard that allows for party-line or multi-drop connections. You would spend a lot of time looking for all the information that the book collects in one place. If you plan to use a serial port in any sort of application, buy this book. It should go on your bookshelf alongside Axelson's earlier book, Parallel Port Complete. -- Test & Measurement World, October 1998

Excerpt. © Reprinted by permission. All rights reserved.
From Chapter 6, Linking Two Devices with RS-232:

Port-powered Circuits

Some low-power circuits that connect to an RS-232 port don't need an external power supply. Instead, they draw all the power they need from the interface itself.

The power comes from unused outputs. To meet the standard, an RS-232 driver's output must be at least 5V with a 3,000-ohm load. From this, we can use Ohm's law to deduce that each output can source at least 1.6 milliampere at 5V. In practice, most RS-232 outputs exceed the minimum, but staying within the specification will ensure that a circuit will work on any port.

Using Signals as a Power Source

Figure 6-7 shows ways of using RS-232 outputs as a power source. When in the On state, RTS and DTR are between +5 and +15V. To set the signals to On in Visual Basic, set MSComm's RTSEnable and DTREnable properties to True.

Figure 6-7A shows a simple unregulated output. When an output is positive, it can serve as a positive voltage source. To double the output current, tie two lines together as shown, with a 1N5819 Schottky diode in each line. This prevents current from feeding back into the interface if the voltages differ. You can use any rectifier diodes, but Schottkys have a lower forward voltage than other silicon diodes.

You can even use the TD line as a power source by setting the Break signal, but of course this prevents you from using the line for data. However, this technique might be useful if you're using the port as a synchronous interface, using handshaking lines for the clock and data.

Regulating the Voltage

Adding a high-efficiency regulator results in a steady output voltage with little wasted power. Figure 6-7B shows a regulated 5V output using the MAX667 low-dropout, linear regulator. The input can be as high as 18V, and it needs to be just 10 millivolts greater than the output, so it will work with most ports. The regulator's quiescent current is under 100 microamperes with a load of several milliamperes.

For a circuit that will work even if the RS-232 output drops below 5V, use the MAX770, which is a switching regulator that has a 5V output with an input between 2V and 16V. The '770 requires several external components, including an inductor and output transistor. If you need only one or a few supplies, Maxim has an inexpensive evaluation kit containing a PC board with all of the components installed.

Another option for port power is to use a lower regulated voltage, either by connecting voltage-divider resistors between Vout, Set, and Gnd as described in the MAX667's data sheet, or by using a regulator with a lower fixed output such as the 3V MAX689.

Because you can count on getting at most a few milliamperes from the port, use care in choosing components that will use port power. Use the lowest-power components you can find, and use a 3V supply if possible.

Customer Reviews

Serial Port Complete is for the Visual Basic user
The book Serial Port Complete is an excellent review of the hardware and signal handling aspects of using the RS-232 and RS-485 systems. It deals well with many of the "rules of thumb" that many have had to learn the hard way over time. The book is limited in its help for the PC user. While it has many usefull examples for the Visual Basic user, most of these can not be extended to the C++ user in a simple clean manner. The Section on using the Windows API's is much too simplified to actually use it for anything usefull (even the author indicates it is limited).

Title Matches Content
I bought the book hoping that it would cover RS-485 well enough for me to use it as a reference for my next project. I wasn't disappointed. It has all the needed information.

The really nice thing I didn't expect was the helpful "guidelines for trouble-free RS-485 links", which included hints on how to deal with cable delay, impedance, termination, reflections, noise, topologies, circuit protection, etc...

I'm not sure how some of these other reviewers were disappointed. The book is very detailed (for the expert), but still easy to read (for the beginner). There is information about how to use microcontrollers and PCs, but it doesn't come at the cost of information on serial communication. In fact, I found that some of the examples using microcontrollers gave me a few ideas for my project.( )

BASIC is a completely logical language to use for showing examples in this book. It is simple and concise. Anyone who complains about it is a zealot, fighting some language war.

an excellent book, must read!
well, i was doing a project that required some very simple interface with a serial device, this book was the only book i brought and it coved more than enough material to make my project work.

about the VB code, well, what i can say, I was using VB.....

well, the book had a very in depth cover of the hardware and the standard of the rs232c. If you want to know how the electronics works, this is the book for you.

if you just want some quick and dirty tricks to make the connection work, this book will also do. as i said early, it had VB examples. in 15 minutes, you will know the basics, and programing in no time!